Driver weight - effect on on turn-in (911).

[Manks]

911s are quite sensitive to the weight over the front wheels when cornering. I.e. they turn in sharper if weight is transferred forwards.

Given that the driver's mass is on one side, it seems to me that turn-in should be different left to right. But is it?

I sometimes think my car turns in sharper left than right. But this could be due to several factors (including imagination).

Is there any logic in my thinking at all?

[Phooey]

Manks said:

Is there any logic in my thinking at all?

Yep. It's the only excuse for a fat bint in the passenger seat.

[IMI A]

get a geo by CG. Turn in should be the same both ways.

[LaurasOtherHalf]

Isn't this what a "corner weight" session is for?

On a completely unrelated note I always used to be able to drift my MR2 easier in one direction, it was only when my race license instructer told me he had one I thought to ask. Down to the transverse engine location apparently making one side much heavier affecting weight transfer, unequal driveshafts didn't help either he reckoned. Makes sense.

[Manks]

IMI A said:

get a geo by CG. Turn in should be the same both ways.

It might be. It might be my imagination or it might be because I steer differently left and right. If there is a difference it is very subtle. But I got to thinking about whether a car with a light front end and a lot of extra weight on one corner would inherrently handle differently left and right.

[Manks]

Phooey said:

Yep. It's the only excuse for a fat bint in the passenger seat.

But if I went everywhere with you in the passenger seat people would start to talk. And Zyp would fly into a jealous rage.

[nickfrog]

Just need to use ballast when the car is set-up, it's standard practice in the industry. And CG haven't invented the concept nor have the exclusivity of ballasting.

I appreciate how good they are but I get so tired of the systematic worshipping of CG...

[keep it lit]

lhd

[graemel]

Unless things have changed. Corner weights on a 911 are done with half a tank of juice and no driver or ballast. Single seaters are with driver or ballast.

[Pickled Piper]

Assymetry in handling can be, as you suggest, due to the weight of the driver. Can also be due to the camber of the road and sometimes torque steer effects.

Pp

[Manks]

Pickled Piper said:

Assymetry in handling can be, as you suggest, due to the weight of the driver. Can also be due to the camber of the road and sometimes torque steer effects.

Pp

That's what I thought.

Camber is quite significant I think.

[keep it lit]

Manks said:

Camber is quite significant I think.

critical

[Zyp]

Manks said:

But if I went everywhere with you in the passenger seat people would start to talk. And Zyp would fly into a jealous rage.

Why in Gods name would I be jealous of a chunky bloke sitting in your passenger seat?

___________________________


Does the position of the fuel tank and quantity of fuel therein, have any bearing on turn-in?

[anonymous-user]

graemel said:

Unless things have changed. Corner weights on a 911 are done with half a tank of juice and no driver or ballast. Single seaters are with driver or ballast.

Normally done with ballast in driver's seat - at least mine was.

[LeoSayer]

If uoi can't notice the difference between a full fuel tank and empty one then you certainly won't notice the difference between a fat bloke and a thin one.

[Zyp]

LeoSayer said:

If uoi can't notice the difference between a full fuel tank and empty one then you certainly won't notice the difference between a fat bloke and a thin one.

Yeah...well, I'm no driving God.

I'll assume the fuel tank is bang in the middle of the car, then.

As an aside, I had a very large, robust friend (no, not Phooey or Manks) in the passenger seat of my Spyder - bloody hell I could tell the difference.

[mrdemon]

IMI A said:

get a geo by CG. Turn in should be the same both ways.

Geo will not help, getting the car corner weighted will though.

[SFO]

PDCC would eliminate any unevenness in weight, won't it?

[fioran0]

drmark said:

Normally done with ballast in driver's seat - at least mine was.

Absolutely, half tank and weight in the drivers seat for a corner balance

[baz1985]

68kg is OE Porsche driver weight. At >68.5kg, the warranty is invalidated!